RT Journal Article
T1 Apparent auxetic to non-auxetic crossover driven by Co2+ redistribution in CoFe2O4 thin films
A1 Ferreiro Vila, Elías
A1 Iglesias Bernardo, Lucía
A1 Lucas del Pozo, Irene
A1 Varela Domínguez, Noa
A1 Bui, Cong Tinh
A1 Rivas Murias, Beatriz
A1 Vila Fungueiriño, José Manuel
A1 Jiménez Cavero, Pilar
A1 Magén, Cesar
A1 Morellón, Luis
A1 Pardo Castro, Víctor
A1 Rivadulla Fernández, José Francisco
AB Oxide spinels of general formula AB2O4 (A = Mg2+, Fe2+; B = Al3+, Cr3+, etc.) constitute one of the most abundant crystalline structures in mineralogy. In this structure, cations distribute among octahedral and tetrahedral sites, according to their size and the crystal-field stabilization energy. The cationic  arrangement determines the mechanical, magnetic, and transport properties of the spinel and can be influenced by external parameters like temperature, pressure, or epitaxial stress in the case of thin films. Here, we report a progressive change in the sign of the Poisson ratio, ν, in thin films of CoFe2O4, defining a smooth crossover from auxetic (ν < 0) to non-auxetic (ν > 0) behavior in response to epitaxial stress and temperature. Microstructural and magnetization studies, as well as ab initio calculations, demonstrate that such unusual elastic response is actually due to a progressive redistribution of Co2+ among the octahedral and tetrahedral sites of the spinel structure. The results presented in this work clarify a long standing controversy about the magnetic and elastic properties of Co-ferrites and are of general applicability for understanding the stress-relaxation mechanism in complex crystalline structures.
PB AIP Publishing
YR 2019
FD 2019
LK http://hdl.handle.net/10347/21351
UL http://hdl.handle.net/10347/21351
LA eng
NO Ferreiro-Vila, E., Iglesias, L., Lucas del Pozo, I., Varela-Domínguez, N. et al. (2019). Apparent auxetic to non-auxetic crossover driven by Co2+ redistribution in CoFe2O4 thin films. "APL Materials", 7, 031109
NO This work has received financial support from Ministerio de Economía y Competitividad (Spain) under Project No. MAT2016-80762-R and MAT2017-82970-C2-R, Xunta de Galicia (Centro singular de investigación de Galicia accreditation 2016-2019, No. ED431G/09), the European Union (European Regional Development Fund-ERDF), and the European Commission through the Horizon H2020 funding by H2020-MSCA-RISE-2016-Project No. 734187–SPICOLOST. I.L.d.P. and B.R.-M. thank the funding under the ESTEEM2 project and the researchers L.A. Rodríguez and E. Snoeck for preliminary Lorentz Microscopy (L.M.) and electron holography (EH) studies in CoFe2O4 samples synthesized by PAD method performed at CEMES (Toulouse)
DS Minerva
RD 27 abr 2026